Disease burden due to PM2.5 pollution before and after air quality improvement in Shijiazhuang / 环境与职业医学

Background Air pollution has gradually become a major environmental and public health problem faced by countries around the world. Hazy weather not only affects the health of the population, but also poses a threat to social and public safety. China has successively promulgated policies such as the "Ten Articles on Atmosphere" and the Three-year action plan to fight air pollution, aiming to improve ambient air quality. It is clear that the Beijing-Tianjin-Hebei region has accomplished the set targets and improved air quality according to the environmental monitoring data of 2017. Objective To assess air quality improvements through the evaluation of the disease burden due to fine particulate matter (PM2.5) pollution in Shijiazhuang City before and after the air quality improvement from 2014 to 2021, including fatalities and health economic losses attributed to PM2.5 pollution. Methods Data on causes of death, PM2.5 concentrations, the number of permanent residents at the end of the year, gross regional product, and disposable income per capita in urban areas of Shijiazhuang were collected from 2014 to 2021. Total, non-accidental, circulatory, and respiratory deaths due to PM2.5 pollution were estimated by global exposure mortality models (GEMM). Health and economic losses due to selected diseases were calculated by value of statistical life (VOSL). Results During the study period, the average annual concentration of PM2.5 in Shijiazhuang was highest in 2014, and began to decline year by year in 2017, but all exceeded the current national limit of the second level of ambient air quality standards (35 μg·m−3). The total deaths, non-accidental deaths, circulatory disease deaths, and respiratory disease deaths attributed to PM2.5 pollution from 2014 to 2021 were 41326, 40246, 21792, and 5022, respectively; the associated health economic losses were 37.362, 36.369, 19.695, and 4.535 billion yuan, respectively. From the perspective of improved air quality, both the number of attributed deaths and health economic losses had declined in a volatile manner since 2017, with a significant decrease in 2019. If the average annual concentration of PM2.5 reached the second-level limit of China's ambient air quality standard (35 μg·m−3), the total deaths, non-accidental deaths, and deaths from circulatory diseases and respiratory diseases due to PM2.5 pollution would deducted by about 17000, 16000, 9000, and 2000, respectively; the corresponding health and economic losses would decreased by 15.201, 14.761, 7.959, and 1.859 billion yuan, respectively. If the average annual concentration of PM2.5 reached the latest PM2.5 air quality guidelines (5 μg·m−3) proposed by the World Health Organization, the total deaths, non-accidental deaths, circulatory disease deaths, and respiratory disease deaths due to PM2.5 pollution would deducted by 36000, 35000, 19000, and 4000, respectively, and the corresponding health and economic losses would reduced by 32.673, 31.796, 17.211, and 3.969 billion yuan, respectively. Conclusion PM2.5 pollution can lead to severe mortality burden and economic loss. Under the implementation of the State Council's "Ten Articles on Atmosphere" and the Three-year action plan to fight air pollution, Shijiazhuang's PM2.5 concentration and health economic losses have been significantly reduced, and further control of PM2.5 pollution can achieve greater health benefits and economic gains, affirming the positive results of local air pollution prevention work.

Three Novel CRF01_AE/CRF07_BC Recombinant Forms of HIV-1 Identified in Shijiazhuang City, China.

BACKGROUND: Hebei, a province with a low Human Immunodeficiency Virus (HIV) prevalence, is also a region with the most abundant HIV-1 genetic diversity. HIV-1 recombinant forms have been the key factor influencing the effectiveness of HIV-1 control and therapy. OBJECTIVES: We aimed to study inter-subtype recombinant structures of new HIV-1-second generation recombinant forms. METHODS: Monitoring the HIV-1 subtype by phylogenetic and recombinant breakpoint analyses are the two most frequent methods among men who have sex with men (MSM). Here, three near full-length genomes (NFLGs) were obtained from HIV-1 seropositive MSM in Shijiazhuang City, China, who have never received antiretroviral therapy in 2021. RESULTS: Phylogenetic analysis indicated that three NFLGs were novel inter-subtype recombinant forms between CRF07_BC and CRF01_AE. For the NFLG 21S009, four CRF07_BC gene fragments were inserted into the pol, vif-vpr, vpu-env, and nef-3` LTR gene regions within a CRF01_ AE backbone, respectively. For the NFLG 21S095, four breakpoints were identified in HIV-1 pol and vpu regions. The NFLG 21S370 contained four gene recombinant breakpoints within HIV-1 pol and vpu-env gene regions. Of these three NFLGs, the NFLG 21S009 contained the most breakpoints, distributed in the pol, vif, vpr, vpu, env, and nef regions, respectively. In the gag-pol regions, three NFLGs had only one CRF07_BC gene fragment inserted into gene points between 4250 and 4792. CONCLUSION: Our findings provide strong evidence that the surveillance of novel recombinant forms is necessary for the increase in better control of HIV.

Spatio-temporal evolution and trend prediction of urban ecosystem service value based on CLUE-S and GM (1,1) compound model.

Ecosystem service value (ESV) is a significant indicator related to regional ecological well-being. Evaluating ESV premised on continuous time series land benefit data can provide an accurate reference for regional ecological civilization construction and sustainable development. Taking Shijiazhuang, the capital city of Hebei Province as an example, the study analyzed land use changes based on the land use data of the continuous time series from 2000 to 2020 and introduced a socio-economic adjustment factor and biomass factor adjustment factor to construct a dynamic assessment model of ecosystem service value. The spatiotemporal changes of the ecosystem service value in Shijiazhuang City were evaluated, and the dynamic prediction of the ecosystem service value was made using the CLUE-S model and the GM (1,1) model. (1) The changes in the overall ESV and spatial pattern in Shijiazhuang are strongly linked to the change in land use, and the contribution of cultivated land, woodland, and grassland to ecosystem service value exceeds 90%. (2) Between 2000 and 2020, the value of ecosystem services illustrated a dynamic change and gradually declined, with the total amount falling from 28.003 to 19.513 billion yuan. Among individual ecosystem services, the value of regulation services suffered the most serious loss. (3) CLUE-S and GM (1,1) perform well in the prediction of ESV. The prediction outcomes illustrate that the ecosystem service value of Shijiazhuang will continue to decline by 2025, and the ecosystem value will drop to 16.771 billion yuan. This research may offer a reference for the dynamic assessment of ESV of the continuous sequence and help to promote regional ecological protection and sustainable development.

COVID-19 transmission driven by age-group mathematical model in Shijiazhuang City of China.

Background: A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination, host, and non-pharmaceutical interventions (NPIs). Herein, we investigated the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City, Hebei Province in Northern China as research objective. In addition, we established a with age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios. Methods: All reported symptomatic cases of Shijiazhuang epidemic (January 2-February 3, 2021) were investigated in our study. The cases were classified by gender, age group and location, the distributions were analyzed by epidemiological characteristics. Furthermore, the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios. Results: Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11, 2021, which was implemented with strong NPIs by local government and referred as baseline situation in this study. The research results showed that R0 under baseline situation ranged from 4.47 to 7.72, and Rt of Gaocheng Distinct took 3.72 with 95% confidence interval from 3.23 to 4.35 on January 9, the declining tendencies of Rt under baseline situation were kept till February 3, the value of Rt reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic. This indicated Shijiazhuang epidemic was under control on January 19. However, if the strong NPIs were kept, but remote isolation operated on January 11 was not implemented as of February 9, then the scale of Shijiazhuang epidemic reached 9482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases. The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over (short for G2) under risk-based strategies (Scenario A), 58,048 symptomatic cases for G2 under late quarantine strategies (Scenario B) and 207,124 symptomatic cases for G2 under late quarantine double risk strategies (Scenario C), and that the corresponding transmission tendencies of Rt for three scenarios were consistently controlled on Jan 29, 2021. Compared with baseline situation, the dates for controlling Rt below 1 under three scenarios were delayed 10 days. Conclusions: Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China. The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure. However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic, which should be considered by public health policies in rural areas of mainland China during the dynamic zero-COVID policy.

[Pollution Characteristics and Transport contributions of Ambient Ozone and Volatile Organic Compounds in Southern Hebei Cities].

The "14th Five-Year Plan" period is the key stage for southern Hebei cities (Shijiazhuang, Xingtai, and Handan) to be removed from the bottom ten of the Air Quality Composite Index. The hourly ozone (O3) data of 15 country-controlled monitoring stations in the southern cities of Hebei Province from April to October 2020, hourly data of three volatile organic compound (VOCs) supersites, and the meteorological data of the same period were used for analysis, combined with the spatiotemporal succession, O3 formation potential (OFP), backward trajectory modeling, and spatial statistical modeling. The results showed the following:firstly, the temporal variations in O3 in southern cities of Hebei Province from April to October presented an inverted "U" shape, and the spatial distribution was high in the south and low in the north. O3 pollution was the most serious in June, with Xingtai (233.8 µg·m-3)>Handan (225.2 µg·m-3)>Shijiazhuang (224.8 µg·m-3). O3 was positively correlated with temperature and wind speed and negatively correlated with humidity and VOCs; furthermore, the ρ(TVOC) from April to October followed the order of Xingtai (274 µg·m-3)>Shijiazhuang (266 µg·m-3)>Handan (218 µg·m-3). The total OFP of alkenes and aromatics accounted for more than half; moreover, the trajectory of O3 pollution in southern cities of Hebei Province showed spatial directionality and relevance. The highest mass concentration of O3 (198.92 µg·m-3) was in the trajectory from Shijiazhuang to Xingtai, and the highest frequency of O3 pollution was in the trajectory from Handan to Xingtai. Moreover, the transmission contributions of O3from Xingtai to Shijiazhuang agglomerations were high (27.39%), and Handan played a significant role in the transmission contribution of O3 to Xingtai (32.76%).

Levels, distribution characteristics, and sources of heavy metals in indoor dust in Shijiazhuang, China.

Heavy metals in indoor dust are associated with health risks in humans. However, in Shijiazhuang, a city in northern China with severe haze, no research has been published on this topic. To determine the content, distribution characteristics, and sources of heavy metals in indoor dust in the city of Shijiazhuang, indoor dust samples from 33 sampling points in the main urban area of Shijiazhuang were collected and tested. Concentrations of Cu, Ni, Cr, Zn, Cd, and Pb were 87.0, 35.1, 104.4, 568.0, 1.980, and 187.6 mg·kg-1, respectively; their levels have been discussed statistically in comparison with the reported values in other cities in China. The sources of heavy metals were analyzed using enrichment factor, correlation coefficient, and principal component analysis. The results showed that the levels of all six elements in indoor dust in Shijiazhuang exceeded the background values of soil in Hebei Province. Among these, Cd, Pb, and Zn were significantly enriched. The enrichment factors of Cu, Ni, and Cr were below 10, and their levels at different sampling points were similar, indicating their geogenic source. The corresponding pollution levels of Cd, Pb, and Zn were relatively high, and their levels at different points were significantly different and correlated, indicating that they were derived mainly from transportation. Additionally, the level of Zn was significantly affected by the indoor environment. Our findings provide a basis for conducting health risk assessments in the future.

[Ozone Sensitivity Analysis and Control Strategy in Shijiazhuang City in July 2019].

The pollution characteristics of surface ozone and its response to meteorological factors were studied based on monitoring in July 2019 in Shijiazhuang City, China. Furthermore, the WRF-CMAQ model coupled with O3 isopleths (EKMA curves) were applied to explore the non-linear response relationship of O3 to precursors VOCs and NOx, aiming to identify a suitable precursor control strategy. The results showed that the days with the maximum daily 8-hour average ozone concentration (MDA8 O3) exceeded the standard by 70.9%. The nonattainment days were usually accompanied by higher temperature, lower relative humidity, and low winds, and the south and southeast winds occurred frequently. The O3 formation was in the strong VOC-limited regime in the urban area of Shijiazhuang, whereas it was in the NOx and VOCs transition regime in suburban areas. As for the urban area, under the condition of single NOx emission reduction, O3 pollution improved when continuous NOx emission reduction was higher than 50% during the nonattainment days. By contrast, during the non-polluted days, O3 concentrations would not rebound when the reduction ratio of NOx and VOCs was higher than 1. In conclusion, VOCs reduction should be the priority for emission reduction plans in urban areas, whereas all different NOx and VOCs ratios led to a decline in O3 concentration in the suburban areas, and a VOCs:NOx of 1:2 was recommended.

Sociodemographic and Policy Factors Associated with the Transmission of COVID-19: Analyzing Longitudinal Contact Tracing Data from a Northern Chinese City.

To examine how sociodemographic characteristics and non-pharmaceutical interventions affect the transmission of COVID-19, we analyze patient profiles and contact tracing data from almost all cases in an outbreak in Shijiazhuang, China, from January to February 2021. Because of universal testing and digital tracing, the data are of high quality. Results from negative binomial models indicate that the counts of close contacts and secondary infections vary with the cases' age and occupation. Notably, cases under age 18 are causing an increased infection rate among their close contacts and leading to more within-neighborhood secondary infections than adults aged 18-49. Also, county-wide interventions and lockdown are found to be effective at containing the spread of COVID-19. These measures can reduce the number of close contacts that each case has and largely restrict the remaining infections to the case's neighborhood. These results suggest that transmission risks of COVID-19 are associated with the case's sociodemographic characteristics and can be reduced with interventions at the county level. Implications on mitigation measures and reopening plans are discussed.

An investigation of current application status of radiological diagnosis and treatment equipment in medical institutions in Shijiazhuang, China, 2019 / 中国辐射卫生

Objective To investigate the application of radiological diagnosis and treatment equipment and distribution of medical radiation levels in medical institutions at various levels in Shijiazhuang, China in 2019, and to lay a sound foundation for further radiation protection and management. Methods A universally designed questionnaire was used to investigate and compile data on the level of the sampled hospitals, the number of radiation workers, equipment information, the number of outpatients and emergency patients, the number of inpatients, and the frequency of radiological diagnosis and treatment; the application frequency of each radiological diagnosis and treatment item was calculated based on the demographic data of Shijiazhuang. Results In Shijiazhuang, there were 390 medical institutions (excluding dental clinics) certified for radiological diagnosis and treatment, with a total of 4262 radiation workers and 1215 radiological diagnosis and treatment devices; 1.11 radiological diagnosis and treatment devices were available per 10 000 people, and 3.89 radiation workers were available per 10 000 people. The number of annual outpatients and emergency patients was 30 208 471, the number of inpatients was 1 981 295, and the total number of people or times receiving radiological diagnosis and treatment was 5 987 230. The application frequency of medical radiation was 546.70 persons/times per 1000 people, with the highest frequency for X-ray diagnosis (534.63 persons/times per 1000 people), followed by diagnosis and treatment with nuclear medicine (6.16 persons/times per 1000 people), and the lowest frequency for radiotherapy (1.17 persons/times per 1000 people). In terms of regional distribution, the highest frequency of medical radiation fell in Yuhua District (1602.97 persons/times per 1000 people), and the lowest frequency fell in Shenze County (203.21 persons/times per 1000 people). Conclusion The development of medical radiation is imbalanced in Shijiazhuang, with high-quality medical resources concentrated mainly in the main urban area, thus resulting in long-term overworking of hospital staff and equipment in some areas. The government and health administration departments should strengthen macro-control and the rational allocation of medical resources; medical institutions at various levels should rationally use radiological diagnosis and treatment equipment, strengthen judgments on the justness of radiation, and strengthen the training of radiation workers on protection knowledge and radiation protection optimization.

Analysis of prescription and medication rules of traditional Chinese medicine in the treatment of the coronavirus disease 2019 based on traditional Chinese medicine inheritance support platform / 中华危重病急救医学

Objective:To analyze the rules of medication and principles of formulas for the treatment of coronavirus disease 2019 (COVID-19) using the traditional Chinese medicine inheritance support platform (V2.5).Methods:The clinical data, including gender, age, clinical symptoms, frequency of traditional Chinese medicine medication and prescription information, of patients with COVID-19 and asymptomatic infection who were admitted to Hebei COVID-19 designated hospital supported by medical team of First Affiliated Hospital of Hebei University of Chinese Medicine from January to March 2021 were collected. The information data were input into the traditional Chinese medicine inheritance support platform (V2.5). The data mining and analysis were realized by the integrated association rules and complex entropy clustering analysis methods of the software, including the analysis of the frequency of each drug use, drug meridian, taste, and prescription rules, and the new prescriptions were developed.Results:A total of 564 patients (564 prescriptions) were enrolled, involving 200 Chinese herbs, including 357 cases of common COVID-19 and 207 cases of asymptomatic infection. The proportion of women with common COVID-19 was high, and the high incidence age group was 51-70 years old. There was no significant difference in gender of asymptomatic infection, and the high incidence age group was 1-20 years old. The main clinical manifestations of most patients were head heavy and cough, followed by low fever and cough with sputum, the main tongue coating and pulse pattern were similar in both types of patients. The frequency of traditional Chinese medicine used in patients with common type of COVID-19 from high to low was liquorice root (326 times), indian bread (264 times), pinellia tuber (263 times), bitter apricot seed (236 times), baical skullcap root (229 times), gypsum (205 times), agastache rugosus (201 times), dried tangerine peel (194 times), ephedra (184 times), and Chinese thorowax root (163 times), while that used by asymptomatic infection were baical skullcap root (174 times), liquorice root (142 times), medicated leaven (137 times), agastache rugosus (127 times), pinellia tuber (114 times), Chinese thorowax root (100 times), officinal magnolia bark (91 times), atractylodes rhizome (89 times), peony root (84 times), and milkvetch root (83 times). The two types of patients were mainly treated with warm, cold and flat drugs, and the nature and taste were mainly pungent, bitter and sweet. The meridian tropism of drugs was mainly lung, spleen and stomach. High frequency drug formulation mainly included drugs for resolving turbidity and detoxification. At the same time, seven new prescriptions for common COVID-19 and four new prescriptions for asymptomatic infection were developed.Conclusions:The primary reason for the COVID-19 occurrence and development is turbidity-toxin and the qi of plague, and resolving turbidity and detoxication are the basic treating principle. On the basis, for patients with common COVID-19, symptomatic treatment such as relieving exterior syndrome, clearing heat, resolving phlegm, and antitussive drugs should be taken into account at the same time, while the treatment of asymptomatic infections should focus more on supporting the body and eliminating the harmful pathogens.

[Spatio-Temporal Characteristics and Potential Source Areas of Seasonal Atmospheric Pollution in Shijiazhuang].

In order to systematically study the transmission characteristics of seasonal and typical pollutants in Shijiazhuang, hourly data of ground-level pollutants(PM2.5, PM10, O3, NO2, SO2, and CO) from 46 state-and provincial-controlled stations, and meteorological(temperature, humidity, and wind speed) data from 17 counties in Shijiazhuang City from December 2018 to November 2019 was analyzed. The interpolation(IDW) and correlation analysis were applied to seasonal and temporal spatial patterns of pollutant concentration. The backward trajectories analysis was performed to explore the seasonal transmission pattern and potential source areas of pollution in Shijiazhuang by combining with the global data assimilation system(GDAS). The results indicate that the different seasons have characteristic pollutants, as follows:spring(PM10, 48.91%), summer(O3, 81.97%), autumn(PM10 and PM2.5, 47.54% and 32.79%), and winter(PM2.5, 74.44%), which are related to the variation of meteorological conditions. Furthermore, the PM10(spring) concentration correlated negatively with the wind speed, presenting a high distribution in the northwest and low in the southeast, with a southerly transmission direction(53.32%). Central and southern Hebei, central and northern Henan, and central Shanxi are the potential sources of pollution(WPCWTij ≥ 160 µg·m-3), impacting western Shandong and northwest Shanxi(WPSCFij ≥ 0.3) with PM10. Moreover, the O3(summer) concentration correlated positively with temperature, and negatively with humidity. The southeast-south(54.24%) is the source direction of the transmission, and the potential source of O3 pollution is an arc area with Shijiazhuang in the center and Cangzhou and Heze as the double wings. Lastly, the PM2.5(autumn and winter) concentration correlated positively with humidity, and the winter concentration shows an increasing gradient from west to east. The trajectories of PM2.5 clustered the source directions:autumn(northeast-southeast, 74.75%), winter(northwest, 55.47%); central and southern Hebei, central and western Shanxi and northern Henan are the concentrated sources of potential pollution(WPCWTij ≥ 180 µg·m-3).

[Spatio-Temporal Evolution Characteristics and Source Apportionment of O3 and NO2 in Shijiazhuang].

Ground-level O3, NO2, and meteorological (temperature, humidity, wind speed, precipitation, and sunshine duration) data from 18 counties in Shijiazhuang City from 2014 to 2017, and volatile organic compounds (VOCs) data for Summer 2017, were analyzed to explore the spatial patterns, evolution, influencing factors, and source apportionment of O3 and NO2 in Shijiazhuang City. Network analysis and inverse distance weighted (IDW) spatial autocorrelation and backward trajectories analyses were performed. The results indicate that O3 concentrations increased between 2014 and 2017, and monthly variations showed a unimodal trend. The typical period of peak O3 pollution (O3 ≥ 160 µg·m-3) was from May to September, characterized by high temperatures, low humidity, weak winds, and strong solar radiation. The O3 concentrations were negatively correlated with the NO2. Furthermore, O3 concentrations increased year-on-year since 2015 in main urban area, and the dominant pollutant type had changed from NO2 (2014 to 2016) to VOCs (2016 and 2017). However, the O3 concentration of county-areas limited by the VOCs. The main factors affecting O3 concentrations were industry, agriculture, economy, and population, and centers of O3 pollution associated with secondary industry appeared in the main urban areas of Shijiazhuang and Luancheng. Moreover, VOCs trajectories during the summer monitoring period were clustered in three source directions:(A) East-northeast, 26.67%; (B) Northwest-west, 43.33%; and (C) Southeast-south, 30%). Trajectories (A) and (C) were the dominant directions of VOC transmission (east-southeast).

Changes in nitrate accumulation mechanisms as PM2.5 levels increase on the North China Plain: A perspective from the dual isotopic compositions of nitrate.

Nitrate (NO3-) has become recognized as the most important water-soluble ion in fine particulate (PM2.5), and has been proposed as a driving factor for regional haze formation. However, nitrate formation mechanisms are still poorly understood. In this study, PM2.5 samples were collected from September 2017 to August 2018 in Shijiazhuang, a city located on the North China Plain, and NO3-concentration, δ18O-NO3- and δ15N-NO3- values in PM2.5 were analyzed. NO3- concentrations increased as PM2.5 levels increased during both polluted and non-polluted days over the entire year. δ18O-NO3- values during cold months (63.5-103‰) were higher than those during warm months (50.3-85.4‰), these results suggested that the nitrate formation pathways shifted from the NO2 + OH (POH) in warm months to the N2O5 + H2O (PN2O5) and NO3 + VOCs (PNO3) pathways in cold months. Especially during cold months, δ18O-NO3- values increased from 65.2-79.9‰ to 80.7-96.2‰ when PM2.5 increased from ∼25 to >100 µg/m3, but when PM2.5 > 100 µg/m3, there were relatively small variations in δ18O-NO3-. These results suggested that nitrate formation pathways changed from POH to PN2O5 and PNO3 pathways when PM2.5 < 100 µg/m3, but that PN2O5 and PNO3 dominated nitrate production when PM2.5 > 100 µg/m3. Higher δ15N-NO3- values in warm months (-11.8-13.8‰) than in cold months (-0.7-22.6‰) may be attributed to differences in NOx emission sources and nitrogen isotopic fractionation among NOx and NO3-. These results provide information on the dual isotopic compositions of nitrate to understand nitrate formation pathways under different PM2.5 levels.

Modeling of a coronavirus disease outbreak at the beginning of 2021 in Shijiazhuang， Hebei Province， China / 上海预防医学

Objective:To model an outbreak of coronavirus disease 2019 （COVID-19） in Shijiazhuang and forecast its spread trend. Method:We collected confirmed COVID-19 cases from the Health Commission of Hebei Province during the period of January 2 to January 27， 2021. We built a new model （SEIaIcRK）， including the contribution of asymptomatic cases， based on the traditional SEIR model to explore and analyze the transmission of COVID-19. Results:A total of 863 confirmed cases were reported during the study period （ended on January 27， 2021）. Our model fitted well with the daily cumulative incidence data and showed that the effective reproductive number decreased sharply from 3.80 on January 2 to 1.54 on January 4， then further decreased to <1 afterwards. Our model also predicted that number of COVID-19 cases would not increase after Feb 16， 2021. Conclusion:The SEIaIcRK model can be used to predict the spread trend of COVID-19 in Shijiazhuang. The current COVID-19 countermeasures effectively contain the disease spread.

[Characteristics and Source Apportionment of VOCs and O3 in Shijiazhuang].

To study the composition characteristics and sources of volatile organic compounds (VOCs) in Shijiazhuang City, three national control points were selected to conduct VOCs sampling and analysis from March 2017 to January 2018. The correlation of VOCs through combination with meteorological and ground-level O3 data, and the sources of VOCs were analyzed by positive matrix factorization (PMF). To quantify the pollution period of O3 in summer, its temporal sequence characteristics were studied by wavelet analysis. During the sampling period, the average concentration of ambient total VOCs (TVOCs) was (137.23±64.62) µg·m-3. Haloalkanes were the most dominant VOC compounds, accounting for 31.77% of total VOCs mass, followed by aromatic (30.97%) and oxygenated VOCs (OVOCs, 23.76%). The seasonal variation in VOC concentration followed the trend in winter (187.7 µg·m-3) > autumn (146.8 µg·m-3) > spring (133.24 µg·m-3) > summer (107.1 µg·m-3); the concentration of VOCs shows a trend of increasing gradient from west to east. The O3 concentration correlated negatively with VOCs and NO2, and positively with temperature, sunshine duration, wind speed, and visibility. Changes in meteorological elements were concerned before the occurrence of ozone pollution in summer, especially in 4-5 days in June and 7-8 days during July to August after the occurrence of increasing temperature. Finally six potential sources of VOCs were quantified by the PMF model, including from gasoline emissions (24.78%), diesel vehicle emissions (24.69%), solvent usage (18.64%), the chemical industry (11.87%), regional background (10.84%), and the pharmaceutical industry (9.17%). Ozone formation potential (OFP) contribution of emission sources of gasoline and diesel vehicles (54.98%) was over half of the total contribution. Meanwhile, these findings illustrated that control of vehicle emissions and industrial sources would be an important way to reduce VOCs concentrations and improve air quality in Shijiazhuang.

Temporal variations and source apportionment of volatile organic compounds at an urban site in Shijiazhuang, China.

Shijiazhuang, the city with the worst air quality in China, is suffering from severe ozone pollution in summer. As the key precursors of ozone generation, it is necessary to control the Volatile Organic Compounds (VOCs) pollution. To have a better understanding of the pollution status and source contribution, the concentrations of 117 ambient VOCs were analyzed from April to August 2018 in an urban site in Shijiazhuang. Results showed that the monthly average concentration of total VOCs was 66.27 ppbv, in which, the oxygenated VOCs (37.89%), alkanes (33.89%), and halogenated hydrocarbons (13.31%) were the main composite on. Eight major sources were identified using Positive Matrix Factorization modeling with an accurate VOCs emission inventory as inter-complementary methods revealed that the petrochemical industry (26.24%), other industrial sources (15.19%), and traffic source (12.24%) were the major sources for ambient VOCs in Shijiazhuang. The spatial distributions of major industrial activities emissions were identified by using geographic information statistics system, which illustrated the VOCs was mainly from the north and southeast of Shijiazhuang. The inverse trajectory analysis using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and Potential Source Contribution Function (PSCF) clearly demonstrated the features of pollutant transport to Shijiazhuang. These findings can provide references for local governments regarding control strategies to reduce VOCs emissions.

Rayleigh based concept to track NOx emission sources in urban areas of China.

Despite the implementation of some effective measures to control emissions of nitrogen oxides (NOx = NO + NO2) in recent years, the ambient NOx concentration in urban cities of China remains high. Therefore, a quantitative understanding of NOx emission sources is critical to developing effective mediation policies. In the present study, the dual isotopic compositions of nitrate (p-NO3-) in fine-particle aerosol (PM2.5) collected daily at a regional scale (Beijing-Tianjin-Shijiazhuang) were measured to better constrain the NOx emission sources. The specific focus was on a typical haze episode that occurred simultaneously in the three urban cities (October 22-29, 2017). It was found that the nitrogen isotopic values of nitrate in PM2.5 (hereafter as δ15N-NO3-) ranged widely from -3.1‰ to + 11.4‰, with a mean value of 3.5 ± 3.7‰. Furthermore, a negative relationship between the δ15N-NO3- values and the corresponded p-NO3- concentrations during the haze period was observed. This implied the preferential formation of 15N-enriched NO3- into a fine-particle aerosol. Taking a different approach to previous publications, the Rayleigh fractionation model was used to characterize the initial isotopic signatures of ambient NOx. After accounting for the δ15N difference between p-NO3- and the source NOx, the estimated initial δ15N-NOx ranged from -20‰ to 0‰, which indicated a cosniderable contribution of non-fossil fuel emissions. The individual contributions of potential sources were further quantified using the Bayesian mixing model, revealing that NOx from coal or natural gas combustion, vehicle exhausts, biomass burning, and the microbial activity contributed 17.9 ± 11.4%, 29.4 ± 19.6%, 29.1 ± 18.9% and 23.5 ± 12.7% to NO3- in PM2.5, respectively. These results highlighted that tightening controls of gaseous NOx emissions from non-fossil sources may represent an opportunity to mitigate PM2.5 pollution in urban cities of China.

[Analysis of Pollution Characteristics and Sources of PM2.5 During Heavy Pollution in Shijiazhuang City Around New Year's Day 2019].

We report on successive haze weather that occurred in Shijiazhuang City, China, from December 30, 2018 to January 15, 2019. There were 12 days of heavy atmospheric pollution during this period, which primarily involved aerosol fine particulate matter (PM2.5). This study analyzes the causes of the pollution using component analysis and by assessing pollution evolution, spatial and temporal distributions of PM2.5, pollution sources, and meteorological factors. The results showed that PM2.5 was mainly composed of secondary inorganic ions (65.4%) that were mainly sourced from coal combustion (24.4%) and industrial sources (23.7%). The contributions of sulfate and secondary inorganic sources increased significantly with increasing pollution. Pollution was affected by unfavorable meteorological conditions (e.g., a low air mass) and by the particular local terrain, static stability, high humidity, and near-ground reverse temperatures from the south-southeast and west-southwest directions. Contaminants from primary sources including coal combustion, industry, and motor vehicle exhausts accumulated quickly in front of the Taihang Mountains. Secondary transformation of gaseous pollutants and increasing moisture absorption of particulate matter increased PM2.5 concentrations. Sulfate explosion also increased pollution. We recommend that as part of emergency responses to heavy pollution events, emissions reduction measures should be implemented to strengthen the control of SO2, NOx, and NH3 emission sources of secondary inorganic precursors, especially SO2 emission sources (i.e., coal etc.). We further propose a strengthen of the management of atmospheric emission sources in Xinle, Wuji, Shenze, Jinzhou, and Xingtang counties in the northeast of the city to reduce the impact of local transmission.

[Characteristics of Haze Pollution Episodes During Autumn and Winter in 2018 in Shijiazhuang].

The mass concentration and chemical composition of fine particles were continuously observed on-line from October 31 to December 3, 2018 at Hebei Key Laboratory of Haze Pollution Prevention and Control in Shijiazhuang. The characteristics of haze pollution in autumn and winter in Shijiazhuang were analyzed. The results showed that during the observation period, four haze pollution episodes occurred with PM2.5 as the primary pollutant, and the maximum daily concentration was 154, 228, 379, and 223 µg·m-3, respectively, reaching a heavy pollution level or above. The main components of PM2.5were water-soluble inorganic ions (WSⅡ) and carbon-containing aerosols, accounting for (60.7±15.6)% and (21.6±9.7)% of PM2.5 mass concentration, respectively. Compared with clean days, the mass concentration of WSⅡ and carbon aerosol during haze pollution increased by 4.4 times and 3.1 times, respectively, which was the main cause of haze pollution. NO3-, SO42-, and NH4+(SNA) were the main components of WSⅡ, accounting for (91.5±17.3)% of the total WSⅡ concentration, of which NO3- took up the highest proportion. The explosive growth of SNA during haze pollution was the main reason for the extremely high PM2.5concentration. Under non-high humidity conditions, the formation rates of unit mass substrates (NO3-, SO42-) were not significantly different, but the transformation of SO42- was significantly promoted after the liquid phase oxidation of SO2 was triggered under high humidity conditions. The atmosphere in Shijiazhuang is rich in NH3, and the molar ratio of n(NH4+) to n(NO3-+2×SO42-) in PM2.5 was greater than 1. The presence of a large amount of NH3 could promote the transformation of NO3- and SO42- and aggravate pollution. During the haze pollution period, the accumulation of primary pollutants from coal and motor vehicles was the main reason for the increase in carbon-containing aerosol. Compared with clean days, the formation of SOC was inhibited. Before the beginning of the warm season, the mobile form was the main pollution source of PM2.5, contributing 30.8% and 39.8% of PM2.5 mass concentration. With the increase of coal combustion emissions, the contribution of coal-fired sources gradually increased to 25.5%, becoming the primary pollution source.

Street Dust Heavy Metal Pollution Source Apportionment and Sustainable Management in A Typical City-Shijiazhuang, China.

Street dust is repeatedly raised by the wind as a secondary suspension, helping heavy metals therein to enter the human body through the respiratory system, harming human health. A detailed investigation was conducted to determine levels and sources of Cd (cadmium), Cr (chromium), Cu (copper), Pb (lead), Zn (zinc), Ni (nick), and Hg (mercury) contamination in street dust from Shijiazhuang, China. The average concentrations of these metals were: Cd, 1.86 mg·kg-1; Cr, 131.7 mg·kg-1; Ni, 40.99 mg·kg-1; Cu, 91.06 mg·kg-1; Pb, 154.78 mg·kg-1, Hg, 0.29 mg·kg-1; and Zn, 496.17 mg·kg-1-all of which were greater than the local soil reference values. The concentrations of the heavy metals were mapped for the three Shijiazhuang ring roads, with the results showing significant differences between each ring. Application of enrichment factors and geoaccumulation indexes showed that there was significant enrichment and accumulation of Cd, Pb, Zn, and Hg. Multivariate statistical analyses showed that Cd, Pb, Zn, and Hg levels were mainly controlled by human activities, while Cr, Ni, and Cu levels were associated with natural sources. Absolute principal component scores with multiple linear regression (APCS-MLR) were applied to facilitate source apportionment. The results showed that the mixed (traffic and industry) group contributed 53.55%, 59.7%, and 62.25% of the Cd, Pb, and Zn concentration, respectively, while the natural sources group contributed 58.01%, 65.09%, and 66.91% of the Cu, Ni, and Cr concentration, respectively. The burning coal group was found to be responsible for 63.38% of the Hg present in the samples. These results provide a useful theoretical basis for Shijiazhuang authorities to address heavy metal pollution management.